High-frequency signaling system



Feb. 1, 127.. 1,615,896

H. A. AFFEL.

HIGH FREQUENCY SIGNALING SYSTEM Filed Dec. 15, 1922 2 Sheets-Sheet l INVEN TOR ZTTORNE 1V Patented l, 1927;

parts STATES HERMAN AFFEL, F BROOKLYN, NEW AND TELEGRAPH COMPANY,

YORK, ASSIGNOR TO AMERICAN TELEPHONE ACORP'KERATION OF NEW YORK.

HIGH-FREQUENCY SIGNALEINQ- SYSTEM.

Application filed December 15, 1925* This invention relates to high frequency signaling systems, and particularly to means for rendering such systems highly selective.

In the development of the radio art, various methods and means have been disclosed, the object of which has been to increase the selectivity of signaling circuits. The best known of all methods consisted in sharply tuning the circuit-so as to make it highly se lective of the frequencies that it was desired to transmit or receive. 1

It is one of the objects of this invention to obtain greater selectivity in the antenna circuits themselves by employing long loop II circuits and by transposing the conductors of the loop, which may be either a completely metallic circuit, or a partly metallic and partly grounded circuit, at intervals properly related to the wave length intended to be received.

Other objects of this invention will be a parentfrom the following description, w en read in connection with the attached drawing, of which Figure 1 shows a trans- 2 posedmetallic loop antenna embodying the -basic principles of this invention.

Fig. 2 shows a transposed loop antenna of a partly metallic and partly rounded type.

Figs. 3 and 4 are curves s owing the selectivity of a non-transposed antenna and a transposed antenna of the type shown in Fi 1, respectively. ig. 5 s ows an arrangement of antennae for transmitting and receiving at the same station, whereb interference ma be prevented by the se ective quality of t eirespective antennae.

And Fig. 6 shows the application of the invention to a system for transmitting carrier frequency signals over a power transmission line simultaneously with the transmission thereover of the power current.

In Fig. 1, the antenna X is represented as transposed at predetermined points indicated by a, b and 0, the number and location of which depend upon the frequency to be selected. At the right-hand end, the antenna is connected with signaling apparatus, which may be of any well-known type of transmitting or receiving apparatus. At the other end of the antenna, there is connected into the circuit an impedance Z which may be pure resistance and which in magnitude equals the characteristic impedance of the 5 antenna at the frequency or frequencies at Serial No. 607,193. which it is intended to be operated- The transpcsitions indicated at the points a, b and c, are spaced at a distance apart de-- pendin upon the length of the wave upon which t e terminal apparatus is'intended to operate. For the particular arrangement of transpositionsshown the loop circuit will be highly selective tofwaves whose length is four times the interval between adjacent transpositions. If the Wave length varies appreciably from this, the various loop current components will be so phased as to tend to oppose and annul each other, and conseq)uently, it will discriminateagainst them.

t be her arrangements in which the distances tween transpositions are unequal will also have selective characteristics, so that selectivity does not depend upon equal spacing of the transpositions. It will be seen that by means. of an antenna constructed in accordance with the principles herein disclosed, the loop circuit may be made highly selective to one fre uency or, if desired, more frequencies an discriminatory to other frequencies that differ materially from the desired frequenciy. or fre uencies.

A orm of 00p antenna for effecting the same pur ose as that shown in Fig. 1 is shown in ig. 2. It consists of a plurality of grounded loop circuits which are inductively related by means of the transformers 18. These transformers are inserted at the common ground connections between adjacent subloops which, taken together, constitute a 100 antenna similar in purpose and in genera principles of operation to that shown in Fig. 1. The common ground connections between the adjacent subloops correspond to the transposition points a, b, and c, of Fig. 1, assuming, of course, that the loops of Figs. 1 and 2 are selective of the same frequency. The direction of the windings of the transformers 18 is such as to cause the current in one winding to flow in opposite direction from that in which the inducing current flows.

A representation of the relative frequency selectivity of nontransposed and transposed circuits is well shown in Figs. 3 and 4, wherein the ordinates represent units of current absorbed by a. circuit which is ezzposed to another circuit over which currents of various frequencies are transmitted. It will be seen from Fig. 3 that if the particular non-transposed loop or circuit is made 8 110 am le,

miles long it will be selective of a number of diflerent frequency bands as, for exis particularly selective of but a single frequency range extending approximately from 7 20,000 to 25,000 cycles. Its transmission di-' vention to a system minishes rapidly on each side of the zone of maximum selectivity and is extremely small below 15,000 cycles and above 30,000,

cycles. Other arrangements of transpositlons in a 100 circuit will produce selectivity curves ifierent from that shown in Fig. 4, and the peaks may be made to occur at more than one point if desired.

Fig. 5 shows the application of this inadapted for the simultaneous transmission and reception of signals without producing interference therebetween. In this system the loop X is connected with the receiving apparatusof the system, and loop X is connected with the transmitting apparatus. Both X and X have connected therewith resistance elements Z and Z equal to the characteristic impedance of their respective antennae, but a diflerent transposition arrangement is applied to the antenna X than to the antenna X so that the former is balanced against the latter, while individually they permit the reception and transmission respectively of the proper frequencies in coordination with the distant stations.

In Fig. 6, the power transmission line 1 has connected therewith a power generator 2 which would normally be of the low frequency type. and at the distantend a load 3. Bridged across the line 1 near the righthand end is an inductance 4 and a condenser 5, and similarly, near the left-hand end an inductance 6 and a condenser 7, the

purpose of the said inductances and condensers being to provide, in effect, a low impedance short circuit of the line for the signaling carrier frequencies. Associated with this tuned section of the line near the left-hand end is a loop 8 having inserted therein a transposition 10 which in combination with the tuned circuit, if the loop is of the proper length and the transposition is properly located, will render the transmission between the said loop circuit and the line highly selective to the carrier fre quency and discriminatory to the power frequency. Bridged across the sides of the loop are the drainage coils 12 and 12' connected to ground by conductor 13, the object of which is to prevent currents set up by potentials induced between the loop cir- 5,000 to 6,000 cycles, 16,000 to 17,000

cuit and ground from affecting the carrier a paratus connected with the loo circuit.

is carrier apparatus which is' esignated 16 may be of any well-known type havin meanss'for detecting the signal superimpo on the carrier wave, and need not be par-- ticularly described here. A similar loop 9 having inserted therein a transposition 11 is inductively related with the transmission line 1 at the other end of the tuned section of the saidline. This loop circuit has brldged across its sides the 00115 14 and 14' which are connected to ground by conductor 15.- Garner apparatus 17, preferabl similar to 16, 1s connected with the said loop c1rcu1tfor transmitting and receiving purposes. I

It will be apparent from the foregoin description of the arrangement shown in I ig.

by the power energy will tend to balance out by virtue of the relatively low frequencies and relatively small phase change in-' volved, but the carrier fre uencies will be efficiently transferred in bot directions between the power lines and the short inducing lines 8 and 9, due to their'considerably greater phase change.

Although this invention has been described as embodied in a particular form and arrangement of parts, it is to be understood that it is capable of embodiment in other and different forms within the spirit and scope of the appended claims.

What is claimed is:

1. A transposed antenna in which the distance between transpositions is a function of the wave length to be transmitted or received.

2. A transposed loop antenna in which the distance between transpositions is a funcion of the wave length to be transmitted or leceived.

3. A loop antenna having transpositions therein, the distance between which is a function of the wave length to be transmitted or received, and having a terminating impedance equal to thesurge impedance of the said antenna. l

4. In a high frequency signaling system, the combination with a loop antenna having transpositions therein, the distance between which is a function of the wave len th to be transmitted or received and terminated in an impedance equal to the surge resistance of the said antenna of a terminal signaling apparatus connected with the said antenna. 5. In a high fr uency signaling system the combination wit a loop antenna having transpositions therein, the distance between which is a function of the wave length to be transmitted, of a second 100 antenna likewise having transpositions herein, the distance between which is a function of the wave length to be received, the frequency of reception differing from the frequency of t f ii' h f 1- m n a 1g requency signa mg s m the combination with a transposed 103 antenna of transmitting apparatus for aplply- 00p us ing signals thereto,a second transposed antenna havin receiving apparatus connected therewit the acing of the transpositlons in the transmitting antenna being different from that in the receiving antenna, the difl'erence bein determined by the difference between t e transmitting and the receiving frequencies.

In testimony whereof, I have signed my name to this specification this 13th day of December, 1922.

HERMAN A. AFFEL. 

